Exercise bike

ABSTRACT

An exercise bike may include a magnetic braking system to resist rotation of a flywheel. The magnetic braking system may be magnets mounted on brackets selectively pivoted relative to the frame to increase or decrease the resistance opposing rotation of the flywheel. The brackets may be pivoted using a brake adjustment assembly joined to the brackets in such a manner that the magnetic forces resisting rotation of the flywheel increase or decrease in a proportional manner over at least a portion of the adjustment range of the brake adjustment assembly. The exercise bike may further include a console that displays information, such as power. The power may be estimated from a look-up table using the crank or flywheel speed of the exercise bike measured using a speed sensor and the tilt angle of the brackets relative to a reference point measured using a power sensor that includes an accelerometer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims, under 35 U.S.C. §119(e), the benefit of U.S.provisional application No. 61/160,241, titled “Exercise Bike” and filedon Mar. 13, 2009, the entire disclosure of which is hereby incorporatedby reference herein in its entirety.

FIELD OF INVENTION

The present invention generally relates to exercise equipment, and moreparticularly to stationary exercise bikes.

BACKGROUND

As with other exercise equipment, exercise bicycles are continuallyevolving. Early exercise bicycles were primarily designed for dailyin-home use and adapted to provide the user with a riding experiencesimilar to riding a bicycle in a seated position. In many examples,early exercise bicycles include a pair of pedals to drive a single frontwheel. To provide resistance, early exercise bicycles and some modernexercise bicycles were equipped with a friction brakes. The frictionbrake typically took the form of a brake pad assembly operably connectedwith a bicycle type front wheel so that a rider could increase ordecrease the pedaling resistance by tightening or loosening the brakepad engagement with the front wheel. However, engagement of the brakespads with the wheel wears down the pads resulting in an undesirablechange of the resistance characteristics of the exercise bike over time.

Another evolution of the exercise bicycle is the replacement orsubstitution of the standard bicycle front wheel with a heavy flywheeland a direct drive transmission. The addition of the flywheel and directdrive transmission provides the rider with a riding experience moresimilar to riding a bicycle because a spinning flywheel has inertiasimilar to the inertia of a rolling bicycle and rider and enhancescardiovascular fitness by requiring the user to continue pedaling sincethere is no freewheeling. These types of exercise bikes are often knownas indoor cycling bikes. Traditionally, these types of exercise bikeshave provided to the user minimal to no information regarding pedalcadence, power, heart rate and so on. This type of information, however,can be useful to a user since these bikes are often used in group ridingprograms at health clubs or for other training where the programs andtraining focus on transitions between various different types of riding,such as riding at high revolutions per minute (RPM), low RPM, changingthe resistance of the flywheel, standing up to pedal, leaning forward,riding within targeted heart rate or power ranges, and so on.

Accordingly, what is needed in the art is an improved exercise bike.

SUMMARY OF THE INVENTION

One embodiment of the present invention may take the form of an exercisebike. The exercise bike may include a frame, a drive train, a flywheeland an adjustment mechanism. The drive train may be operativelyassociated with the frame. The flywheel may be operatively associatedwith the drive train. The adjustment mechanism may include incrementalunits of adjustment for substantially linearly increasing a magneticresistance force on the flywheel.

Another embodiment of the present invention may take the form of anexercise bike. The exercise bike may include a frame, a drive train, aflywheel, a braking system, and a power sensor. The drive train may beoperatively associated with the frame. The flywheel may be operativelyassociated with the drive train. The braking system may be operativelyassociated with flywheel. The power sensor may be operatively associatedthe braking system. The power sensor may include an accelerometer thatmeasures a position of the braking system relative to a predeterminedreference point.

Yet another embodiment of the present invention may take the form of amethod for estimating a power of an exercise bike. The method mayinclude measuring a rotational speed of a flywheel of the exercise bike.The method may further include measuring a tilt angle of a magneticbrake operatively associated with the flywheel. The method may alsoinclude estimating power using the measured rotational speed and themeasured tilt angle.

Still yet another embodiment of the present invention may take the formof an exercise bike. The exercise bike may include a frame, a drivetrain, a flywheel and a braking assembly. The drive train may beoperatively associated with the frame. The flywheel may be operativelyassociated with the drive train The braking assembly may include anadjustment member and a magnetic brake. The adjustment member may definea longitudinal axis. The magnetic brake selectively may be operativelyassociated and selectively operatively disassociated with the flywheelby rotating the adjustment member around the longitudinal axis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of an exercise bike.

FIG. 2 shows a perspective view of a front portion of the exercise bikeof FIG. 1.

FIG. 3 shows a cross-section view of a front portion of the exercisebike of FIG. 1, viewed along section 3-3 in FIG. 2.

FIG. 4A shows an exploded perspective view of a portion of a brakeassembly for the exercise bike of FIG. 1.

FIG. 4B shows an exploded perspective view of another portion of thebrake assembly.

FIG. 5A shows a cross-section view of a front portion of the exercisebike of FIG. 1, viewed along section 5A-5A in FIG. 2.

FIG. 5B shows an enlarged portion of the cross-section view shown inFIG. 5A.

FIG. 5C shows an enlarged portion of the cross-section view shown inFIG. 5A.

FIG. 5D is a cross-section view of a portion of the brake assembly viewalong section 5D-5D in FIG. 3, showing a potential polar alignment ofthe magnets for the exercise bike.

FIG. 6 shows an exploded perspective view of a flywheel for the exercisebike of FIG. 1.

FIG. 7 shows an exploded cross-section view of the flywheel, viewedalong line 7-7 in FIG. 6.

FIG. 8 shows a partial cross-section view of the flywheel similar to theview shown in FIG. 7 except the flywheel is shown in an assembled view.

FIG. 9 shows a cross-section view of the brake assembly of the exercisebike showing the brake assembly in a first position, viewed along line9-9 in FIG. 5A.

FIG. 10 shows a cross-section view of a portion of the brake assemblyviewed along line 10-10 in FIG. 9.

FIG. 11 shows a cross-section view of the brake assembly of the exercisebike similar to the view shown in FIG. 9, showing the brake assembly ina second position.

FIG. 12 shows a cross-section view of a portion of the brake assemblyviewed along line 12-12 in FIG. 11.

FIG. 13 shows a cross-section view of the brake assembly with a frictionbrake engaged with the flywheel.

FIG. 14A shows a schematic of a portion of the brake assembly in a firstposition.

FIG. 14B shows a schematic of a portion of the brake assembly in asecond position.

FIG. 14C shows a schematic of a portion of the brake assembly in a thirdposition.

FIG. 14D shows a schematic of a portion of the brake assembly in afourth position.

FIG. 15 is chart showing percentage of brake movement vs. area of magnetoverlap.

FIG. 16A is a graph showing test data for power versus turns of acontrol knob at a crank speed of 40 rpm for a prototype of an exercisebike having a resistance assembly as shown in FIGS. 2-5D.

FIG. 16B is a graph showing test data for power versus turns of acontrol knob at a crank speed of 60 rpm for a prototype of an exercisebike having a resistance assembly as shown in FIGS. 2-5D.

FIG. 16C is a graph showing test data for power versus turns of acontrol knob at a crank speed of 100 rpm for a prototype of an exercisebike having a resistance assembly as shown in FIGS. 2-5D.

FIG. 17 shows a schematic of a console and monitoring system for theexercise bike of FIG. 1.

FIG. 18 shows a schematic of a power sensor for the exercise bike ofFIG. 1.

FIG. 19 shows an example of a power look-up table for the exercise bikeof FIG. 1.

FIG. 20 shows a flow chart for displaying power information for theexercise bike of FIG. 1.

DETAILED DESCRIPTION

Described herein are stationary exercise or indoor cycling bikes. Theseexercise bikes may include a flywheel rotated by a user via a drivetrain system. Resistance to rotation of the flywheel may be provided byan eddy current brake positioned proximate the flywheel. In someembodiments, the exercise bikes may include a monitoring system fordetermining the flywheel speed and the power output by the user. Suchexercise bikes may further include a console for displaying informationof interest, such as the crank speed and the user's power output.

FIG. 1 shows a perspective view of an exercise or indoor cycling bike100, which may be referred to herein as either of the above. FIG. 2shows a perspective view of a portion the exercise bike 100 with theshrouds removed to show portions of the drive train assembly 102 and theresistance assembly 104. The exercise bike may include a frame 106, aseat assembly 108, a handlebar assembly 110, the drive train assembly102, the resistance assembly 104, a monitoring system (see FIG. 18), anda display system (see FIG. 17). The exercise bike 100 may furtherinclude one or more shrouds or covers 112 joined to the frame 106 tolimit access by a user or others to moving portions of the drive trainassembly 102 and resistance assembly 104.

With continued reference to FIG. 1, the seat assembly 108 may include aseat post 114 adjustably connected to the frame 106 to allow the user toadjust the vertical position of a seat 116 for supporting the user in aseated position. The seat 116 may also be adjustably supported by theseat post 114 to allow the user to adjust the horizontal position of theseat 116. The handlebar assembly 110 may include one or more handles 118for a user to grasp. The handles 118 may take the form of bull horns,aero bars or any other handle used on exercise bikes. The handlebarassembly 110 may further include a handlebar post 120 connected to theframe 106 to allow the user to adjust the vertical and/or horizontalposition of the handles 118.

With reference to FIGS. 1-3, the drive train assembly 102 may include acrank assembly 122 rotatably supported by the frame 106 and a drivetrain connection member 124 for operatively joining the crank assembly122 to the resistance assembly 104. The crank assembly 122 may include acrank or drive ring rotatably mounted on the frame 106 at a bottombracket, crank arms 126 extending from the drive ring, and a pedal 128joined to each crank arm 126 for allowing the user to engage the crankassembly 122. The drive train connection member 124 may be a chain, asshown in FIG. 3, a belt or any other suitable member for transferringrotation of the drive ring to a flywheel 130 of the resistance assembly104.

With continued reference to FIGS. 1 and 2, the resistance assembly 104may include the flywheel 130 and a brake assembly 132. The flywheel 130may be rotatably mounted to the frame 106. The flywheel 130 may befurther joined to the drive ring by the drive train connection member124 such that rotation of the drive ring causes rotation of the flywheel130. The flywheel 130 may be directly joined to the drive ring via thedrive train connection member 124 or may be joined via a clutch, as iscommonly known. The brake assembly 132 may be operatively associatedwith the flywheel 130 to resist or otherwise oppose rotation of theflywheel 130 using an eddy current braking system.

With reference to FIGS. 2-4B, the brake assembly 132 may be include oneor more magnets 134, right and left brackets or arms 136, 138 (which mayalso be referred to as first or second brackets or arms), a brakeadjustment assembly 140 and a friction brake 142. The magnets 134 may bepositioned proximate the flywheel 130 to generate a magnetic field thatresists rotation of the flywheel 130 as the flywheel 130 rotates pastthe magnets 134. To selectively change the position of the magnets 134relative to the flywheel 130, the magnets 134 may be mounted on theright and left brackets 136, 138. The right and left brackets 136, 138may, in turn, be pivotally mounted to the frame 106. The brakeadjustment assembly 140 or adjustment mechanism may be used to pivot orotherwise move the right and left brackets 136, 138 relative to theframe 106. The brake adjustment assembly 140 may also be joined to thefriction brake 142 for selective engagement of the friction brake 142with the perimeter of the flywheel 130 to stop rotation of the flywheel130.

The brake assembly 132 may be used to resist rotation of the flywheel130 as follows. As the flywheel 130 rotates, it passes through amagnetic field generated by the magnets 134. This rotation of theflywheel 130 through the magnetic field creates a force that resistsrotation of the flywheel 130. As the magnets 134 overlap a greaterportion of the flywheel 130, the resistance to the rotation of theflywheel 130 by the magnetic field increases. An increase in theresistance to the rotation of the flywheel 130 rotation requires theuser to exert more energy to rotate the flywheel 130 via the crankassembly 122. The amount of overlap of the magnets 134 with the flywheel130 may be increased or decreased by selectively pivoting the brackets136, 138 relative to the frame 106 using the brake adjustment assembly140.

As the brackets 136, 138 are pivoted in a clockwise direction as viewedfrom the right side of the bike 100, the magnets 134 mounted on thebrackets 136, 138 move towards the flywheel 130. Similarly, as thebrackets 136, 138 are pivoted in a counterclockwise direction as viewedfrom the right side of the bike 100, the magnets 134 mounted on thebrackets 136, 138 move away from the flywheel 130. Movement of themagnets 134 towards the flywheel 130 increases the forces opposingrotation of the flywheel 130 since the amount of overlap of the magnets134 over the flywheel 130 increases, and movement of the magnets away134 from the flywheel 130 decreases the forces opposing rotation of theflywheel 130 since the amount of overlap of the magnets 134 over theflywheel 130 decreases. The friction brake 142 may be utilized torapidly stop rotation of the flywheel 130 by pressing down the brakeadjustment assembly 140 until the friction brake 142 engages aperipheral portion of the flywheel 130. Because the friction brake 142can rapidly stop rotation of the flywheel 130, it may be used as anemergency brake.

FIGS. 2-5B show various views of the exercise bike 100 that implementthe various features of the resistance assembly 104 described above. Thefigures are merely representative of one possible way to implement thesefeatures into an exercise bike 100 and are not intended to imply orrequire these specific components nor limit use of other components toimplement these features.

As discussed above, the brake assembly 132 may include right and leftbrackets 136, 138. The right and left brackets 136, 138 may be pivotallyjoined to the frame 106. Further, the brackets 136, 138 may be joined tomove together. As shown in FIGS. 2 and 3, a free end of each bracket136, 138 may extend from the pivot connection 144 towards the front ofthe bike 100. In some embodiments, the brackets 136, 138 could bepivotally joined to the frame 106 such that the free end of each bracket136, 138 extends towards the rear of the bike 100. The configurationshown in FIGS. 2 and 3, however, may be helpful. Specifically, when thepivot connection 144 is positioned towards the front end of the brackets136, 138 as opposed towards the rear end of the brackets 136, 138 asshown in FIGS. 2 and 3, rotation of the flywheel 130 tends to pull thebrackets 136, 138 undesirably towards the flywheel 130.

The flywheel 130 pulling the brackets 136, 138 towards the flywheel 130is undesirable because the brake adjustment assembly 140 includes a biasmember 148, as described below, that maintains the position of anadjustment member 146 of the brake adjustment assembly 140 by opposingmovement of the brake adjustment assembly 140 towards the flywheel 130.If the brackets 136, 138 are pulled towards the flywheel 130, thebrackets 136, 138 pull the adjustment member 146 towards the flywheel130, which requires a stiffer bias member to maintain the position ofthe adjustment member 146. However, the user must overcome the stiffnessof the bias member 148 to move the adjustment member 146 down towardsthe flywheel 130 in order to engage the friction brake 142 with theflywheel 130. Thus, the bias member 148 should be maintained below apredetermined stiffness so that the user can readily engage the frictionbrake 142 with the flywheel 130 via the adjustment member 146. This goalcan be more readily obtained when the brackets 136, 138 are not beingpulled downward by the flywheel 130 as it rotates, which occurs when thebrackets 136, 138 are pivoted at the front ends of the brackets 136, 138as opposed to their rear ends. Regardless, the brackets 136, 138 may bepivoted about any suitable point to facilitate moving the magnets 134over the flywheel 130.

With reference to FIG. 4B, the right and left brackets 136, 138 may takethe form of plates or the like. Each bracket 136, 138 may include one ormore magnet recesses 150 sized for receiving at least a portion of oneof the magnets 134. Each bracket 136, 138 may be any suitable shape thatallows for one or more magnets 134 to be joined to the plate. As anexample and with reference to FIGS. 2 and 4B, the right bracket 136 maybe a generally triangular plate sized to fit a power sensor (discussedfurther below) and three magnets 134 on the bracket 136. The threemagnets 134 may be aligned on a linear or curved line along an upperportion of the plate. To limit the size of the plate, each magnet 134may be spaced relatively close to adjacent magnets 134. Closely spacingthe magnets 134 also creates a more proportional increase in the forcesopposing the flywheel 130 when overlapping the flywheel 130 with themagnets 134. The power sensor 152 may be connected to a lower portion ofthe plate on an outward facing side of the plate. With reference to FIG.4B, the left bracket 138 may be a generally rectangular plate. Like theright bracket 136, three magnets 134 may be aligned on the left bracket138 on a linear or curved line. Although the shape of each bracketdiffers as shown in FIG. 4B, each bracket 136, 138 could have the sameshape in other versions of the exercise bike.

The brackets 136, 138 may be formed from a conductive metal or othermaterial that allows the magnets 134 to be magnetically joined to thebrackets 136, 138. Alternatively, the magnets 134 could be joined to amagnetic or non-magnetic material using other connection methods such asfriction fit connections, mechanical fasteners, adhesives and so on.Further, although three magnets 134 are shown in figures as joined toeach of the right and left brackets 136, 138, more or less than threemagnets 134 may be joined to each bracket 136, 138.

The magnets 134 used in the brake assembly 132 may be formed from rareearth elements or any other suitable magnetic material. The magnets 134may be circular or any other suitable shape. Circular magnets result ina more uniform positioning of the magnets 134 around the flywheel 130.When using more than one magnet 134, the magnets 134 may be positionedon each bracket such that the pole nearest the flywheel 130 alternatesfrom North to South for each magnet 134 as shown in FIG. 5D. Further,the pole of the magnet 134 facing towards the flywheel 130 on onebracket 136 may be positioned to be opposite the pole facing towards theflywheel 130 of corresponding magnet 134 on the other bracket 138 asalso shown in FIG. 5D. Configuring the magnets 134 in the manner shownin FIG. 5D limits degradation in the resistance experienced by theflywheel 130 compared to configurations in which the poles of themagnets 134 are not positioned in an alternating arrangement as shown inFIG. 5D.

Returning to FIGS. 2 and 4B, the brake assembly 132 may further includea bracket pivot assembly 152 for pivotally joining the right and leftbrackets 136, 138 to the frame 106. Specifically, the bracket pivotassembly 154 may include a pivot member or axle 156, such as a bolt orthe like, received through co-axially aligned bracket pivot holes 158a-c formed in each bracket 136, 138 and in a bracket support member 160extending from the frame 106. A longitudinal axis of the pivot member156 defines a pivot axis around which the brackets 136, 138 pivot. Thebracket pivot assembly 154 may further include right and left bracketbearings 162 a-b received within the right and left bracket pivot holes158 a-b to facilitate the pivoting of each bracket 136, 138 around thepivot axis. To join the bracket bearings 162 a-b to the pivot member156, each brake bracket bearing 162 a-b may define an aperture 164 a-bfor receiving the pivot member 156 therethough. A bracket spring 166 maybe joined to the bracket support member 160 and a bracket 136 tomaintain the relative pivotal position of the brackets 136, 138 relativeto the bracket support member 160 when the brackets 136, 138 are notbeing selectively pivoted or otherwise moved by the user.

With reference to FIGS. 4A and 5A-5C, the brake adjustment assembly 140,which may also be referred to as the adjustment mechanism, may include abiasing member assembly 168, the adjustment member 146, a control knob170, an adjustment bearing member 172 and a link assembly 174. The biasmember assembly 168 may include an upper bias member housing 176 and alower bias member housing 178. The lower bias member housing 178 may bejoined by threads to a lower portion of the upper bias member housing176 to define a bias member housing. The joined upper and lower biasmember housings 176, 178 define a substantially enclosed space forreceiving the bias member 148, such as a spring, and a portion of theadjustment member 146. The bias member 148 biases the adjustment member146 to a predetermined position relative to the frame 106 when notengaged by the user. The bias member 148 should have a sufficientstiffness to maintain the adjustment member 146 in the predeterminedposition when not engaged by the user. The biasing member assembly 168may be received within a space defined by the bike frame 106. Thebiasing member assembly 168 may be joined to the bike frame 106 usingthreads defined on the upper bias member housing 176 or by any othersuitable connection method.

The adjustment member 146 may be a generally cylindrical rod or anyother suitable shaped rod or other elongated member defining alongitudinal axis. A portion of the adjustment member 146 may bereceived within the bias member housing. Proximate an upper end of thebias member 148, the cross-section area of the adjustment member 146transverse to the longitudinal axis of the adjustment member 146 may bechanged to define an engagement surface for engaging the upper end ofthe bias member 148. A washer 180 or the like may be positioned betweenthe upper end of the bias member 148 and engagement surface of theadjustment member 146. Proximate a lower end of the bias member housing,the adjustment member 146 may include a clip groove 182. A clip ring184, such as a E clip, may be received in the clip groove 182. The clipring 184 engages a bottom end of the bias member housing via a secondwasher 186 to maintain engagement of the adjustment member 146 with thebias member 148. A lower portion of the adjustment member 146 may bethreaded for movably joining the adjustment member 146 to the linkassembly 174.

Proximate a lower portion of the adjustment member 146, the adjustmentbearing member 172 may be joined to the bike frame 106 by a suitableconnection method. The adjustment member 146 may be received through abearing aperture 188 defined in the adjustment bearing member 172. Theadjustment member 146 can be rotated within the bearing aperture 188 andcan be moved vertically through the bearing aperture 188. The adjustmentbearing member 172, however, prevents the adjustment member 146 frommoving in directions other than vertical.

The control knob 170 may be joined to an upper portion of the adjustmentmember 146. The control knob 170 provides an object for the user toengage to rotate the adjustment member 146 about the longitudinal axisof the adjustment member 146 and to move the adjustment member 146vertically. As described below, rotation of the adjustment member 146about its longitudinal axis changes the position of the magnets 134relative to the flywheel 130. Moving the adjustment member 134vertically downward allows the friction brake 142 to be engaged with theflywheel 130.

The link assembly 174 joins the adjustment member 146 to the right andleft brackets 136, 138. With reference to FIGS. 4A and 5C, the linkassembly 174 may include right and left links 190 a-b (which may also bereferred to as first and second links) and a link plate 192. Upperportions of the right and left links 190 a-b may be pivotally joined tothe link plate 192. Lower portions of the right and left links 190 a-bmay be pivotally joined to the right and left brackets 136, 138,respectively. The link plate 192 may include a threaded link plate hole194 for joining by threaded engagement the link assembly 174 to theadjustment member 146. Selective rotation of the adjustment member 146about its longitudinal axis moves the link plate 192 along the threadedportion of the adjustment member 146. As the link plate 192 moves alongthe threaded portion of the adjustment member 146, the link assembly 174pivots the brackets 136, 138 relative to the flywheel 130 via connectionof the right and left links 190 a-b to the link plate 192 and the rightand left brackets 136, 138.

With reference to FIGS. 3 and 4B, the friction brake 142 may be a brakepad 196 formed from rubber or other suitable material and joined to abrake pad support 198. The brake pad 196 may be positioned between andjoined to the right and left brackets 136, 138. A lower portion of thebrake pad 196 may be curved to conform to the outer surface of theflywheel 130. Such curving facilitates a more uniform engagement of thelower surface of the brake pad 196 with the outer radial surface of theflywheel 130. The brake pad 196 may also be positioned at an anglerelative to a vertical axis to also cause a more uniform engagement ofthe lower surface of the brake pad 196 with the outer radial surface ofthe flywheel 130.

With reference to FIGS. 6-8, the flywheel 130 may be formed from two ormore materials. An outer radial portion 200 of the flywheel 130 may beformed from a conductive, non-ferrous material, such as aluminum orcopper, and an inner radial portion 205 of the flywheel 130 may beformed from a relatively dense material, such as steel. Use ofconductive, non-ferrous material for the outer radial portion 200 of theflywheel 130 and a relatively dense material for the inner radialportion 205 of the flywheel 130 allows for the eddy current brake effecton the flywheel 130 via use of the magnets 134 while allowing for arelatively smaller overall flywheel 130 for a desired flywheel inertialmass. More particularly, in order to generate, with the magnetic field,forces that resist rotation of the flywheel 130, the portion of theflywheel 130 passing through the magnetic field needs to be formed froma conductive material. Non-ferrous conductive materials, such asaluminum, are preferred over ferrous conductive materials. Aluminum,however, tends to be less dense than other materials, such as steel.Thus, to achieve a desired inertial mass, a flywheel 130 made entirelyfrom aluminum generally needs to be larger than a flywheel 130 made fromsteel. Using a denser material, such as steel, for the inner radialportion 205 and aluminum for the outer radial portion 200 of theflywheel 130 allows for a relatively smaller flywheel 130 to be used onthe exercise bike 100 compared to an all aluminum flywheel 130 whileobtaining the benefits of passing a non-ferrous conductive materialthrough the magnetic field to generate a resistive force to the rotationof the flywheel 130.

With continued reference to FIGS. 6-8, the non-ferrous conductiveportion 200 of the flywheel 130 may be formed into an annular ring. Theinner radial portion 205 of the flywheel 130 may extend a greater radialdistance on one side of the flywheel 130 to define a radial surface forjoining the annular ring to the inner radial portion 205 of the flywheel130. Fasteners 210, such as screws or the like, may be used to join thenon-ferrous portion 200 of the flywheel 130 to the inner radial portion205 of the flywheel 130. The outer and inner radial portions 200, 205 ofthe flywheel 130 could be joined by other connection methods, such aswelds, adhesives and so on. Further, although the flywheel 130 is shownand described as formed from two materials, the flywheel 130 could beformed from a single material, such as aluminum or copper.

Operation of the resistance assembly 104 shown in FIGS. 2-5A will now bedescribed with reference to FIGS. 9-14D. FIG. 9 is a section through 9-9of FIG. 5A, and thus only the left bracket 138 and left link 190 b areshown. FIGS. 11 and 13 are representative cross-sections similar to FIG.9 and are used to show the brake assembly in different positionsrelative to the flywheel 130. FIGS. 10 and 12 are sections through 10-10of FIGS. 9 and 12-12 of FIG. 11, respectively, and are used to show therelative position of the magnets 134 for different positions of thebrake assembly 132 relative to the flywheel 130.

FIGS. 9 and 10 show the brake assembly 132 in an upper or startposition. In this upper position, further upward movement of the leftand right brackets 136, 138 is prevented by engagement of the brackets136, 138 with the frame 106. Also, in this upper position, the magnets134 do not overlap the flywheel 130, and thus the flywheel 130 mayrotate with little or no resistance applied to it by the magnetic brakesystem.

Rotation of the adjustment member 146 in a clockwise direction as viewedfrom above the adjustment member 146 causes the link plate 192 of thelink assembly 174 to move vertically downward along the adjustmentmember 146. The link plate 192 is joined to the bracket members 136, 138by the right and left links 190 a-b. Thus, as the link plate 192 movesvertically downward, it causes the brackets 136, 138 to pivot relativeto the frame 106 in a direction towards the flywheel 130. As the bracketmembers 136, 138 pivot in this direction, the magnets 134 begin tooverlap the flywheel 130. As the overlap increases, the resistanceprovided by the magnets 134 to rotation of the flywheel 130 alsoincreases. Continued rotation of the adjustment member 146 in theclockwise direction as viewed from above the adjustment member 146causes the brackets 136, 138 to gradually progress from the positionshown in FIG. 9 to the position shown in FIG. 11, such that the magnets134 move from a position not overlapping the flywheel 130 as shown, forexample, in FIG. 10 to a position that the magnets 134 overlap theflywheel 130 as shown, for example, in FIG. 12.

To reduce the resistance provided by the magnetic brake, the adjustmentmember 146 may be rotated in a counterclockwise direction as viewed fromabove. Rotation of the adjustment member 146 in this direction causesthe link plate 192 to move upward along the threaded portion of theadjustment member 146. Movement of the link plate 192 upward causes thebrackets 136, 138 to pivot relative to the frame 106 in a direction awayfrom the flywheel 130. As the brackets 136, 138 pivot in this direction,the amount of the overlap of the flywheel 130 by the magnets 134decreases. As the overlap decreases, the resistance provided by themagnets 134 to rotation of the flywheel 130 decreases.

To provide a proportional increase in the opposition forces for a leasta portion of the movement range of the adjustment assembly 140 for eachincremental unit of movement of the adjustment assembly 140, theadjustment assembly 140 may be configured to decrease the movement ofthe magnets 134 towards the flywheel 130 for each incremental unit ofmovement of the adjustment assembly by the user for a least a portion ofthe movement range of the adjustment assembly. For example, theadjustment assembly 140 shown in FIGS. 9-13 allows the user to move themagnets 134 by rotation of the control knob 170. When the user rotatesthe control knob 170 one full revolution, the magnets 134 move towardsthe flywheel 130 from the position shown in FIG. 14A to the positionshown in FIG. 14B. When the user rotates the control knob 170 anotherfull revolution, the magnets 134 move towards the flywheel 130 from theposition shown in FIG. 14B to the position shown in FIG. 14C.

With further reference to FIGS. 14A-14D, the right and left links 190a-b pivot relative to the link plate 192 and the brackets 136, 138 asthe brackets 136, 138 are moved from the position shown in FIG. 14A tothe position shown in FIG. 14D. With reference to FIG. 14A, alongitudinal axis of the right and left links 190 a-b extends at anangle from the longitudinal axis of the adjustment member 146. As thebrackets 136, 138 move from the position in FIG. 14A to the position inFIG. 14D, the right and left links 190 a-b pivot relative to the linkplate 192 and the brackets 136, 138 in a direction that generally alignsthe longitudinal axis of the right and left links 190 a-b with thelongitudinal axis of the adjustment member 146. As the longitudinal axesof the right and left links 190 a-b align more with the longitudinalaxis of the adjustment member 146, the rate the magnets 134 overlap theflywheel 130 for each incremental unit of rotation of the adjustmentmember 146 decreases. In other words, as the magnets 134 overlap agreater portion of the flywheel 130, the rate at which the magnets 134further overlap the flywheel 130 may decrease for a given incrementalmovement of the control knob 170 for at least a portion of theadjustment range of the adjustment member 146 to create a moreproportional increase in the magnetic forces opposing rotation of theflywheel 130.

This non-linear movement of the magnets 134 over a greater portion ofthe flywheel 130 as the magnets 134 overlap more of the flywheel 130creates a more proportional increase in the forces opposing rotation ofthe flywheel 130 for a given incremental movement of the control knob170 within at least a range of the total range of movement of thecontrol knob 170. FIG. 15 shows a graph of a calculated area of magnetoverlap versus percentage of total movement of the adjustment assembly140 for two configurations of an adjustment assembly 140. The data forthe first configuration is identified as “A” in the graph, and the datafor the second configuration is identified as “B” in the graph. Thefirst configuration is based on an adjustment assembly similar to theadjustment assembly shown in FIGS. 9-13. The second configurationdiffers from the configuration shown in the drawings. Some of thedifferences between the second configuration and the first configurationare the brackets 136, 138 of the second configuration were pivoted fromtheir front ends rather than their rear ends and the center of themagnets 134 of the second configuration were aligned along an arc ratherthan along a straight line.

As shown in FIG. 15 with respect to the first configuration, up untilabout 25% percent of the total movement range of the magnets 134 via theadjustment assembly 140, the overlap of the magnets 134, and thus theforces opposing rotation of the flywheel 130, increase in asubstantially non-proportional manner. From about 25% to about 65% ofthe total movement range of the adjustment assembly 140, the overlap ofthe magnets 134, and thus the flywheel opposition force, increases in asubstantially proportional manner, which may take the form of asubstantially linear relationship. Above about 65%, the overlap of themagnets 134, and thus the flywheel opposition force, return toincreasing in a more non-proportional manner. Thus, for a portion ofmovement of the adjustment assembly 140 from about 25% to about 65% ofthe total range of movement of the adjustment assembly 140, the forcesopposing the rotation of the flywheel 130 increase in a substantiallylinear manner relative to the movement of the adjustment assembly 140(i.e., a given incremental movement of the adjustment assembly 140 willcause a proportional incremental increase in the forces opposingrotation of the flywheel 130 throughout this movement range).

The data for the second configuration shows that changing theconfiguration of the brake assembly 132 can result in differing amountsof magnet 134 overlap over the movement range of the adjustment assembly140. More particularly, for the second configuration it took longer forall of the magnets 134 to overlap the flywheel 130 than for the firstconfiguration, thus resulting in less overlap of the flywheel 130 by themagnets 134 in the early stages of the brake's movement through itsrange of movement compared to the first configuration. In bothconfigurations, once all of the magnets 134 began overlapping theflywheel 130, the overlap for additional movements of the brakeincreased at a much greater rate for both configurations.

FIGS. 16A-C show test data for power versus complete turns of anadjustment member 146 for an exercise bike 100 with a resistanceassembly 104 similar to the one shown in FIGS. 2-5D. FIG. 16A shows thepower measured for various turns of the adjustment member 146 at a crankspeed of 40 rpm. FIG. 16B shows the power measured for various turns ofthe adjustment member 146 at a crank speed of 60 rpm. FIG. 16C shows thepower measured for various turns of the adjustment member 146 at a crankspeed of 100 rpm. With reference to FIGS. 16A-16C, it may be noted thatpower increases and decreases in a substantially proportional manner, inthis case in a substantially linear manner, from approximately 4 to 8full complete turns. Below 4 complete turns, the power tends to increaseand decrease in a less proportional manner at each rpm. Aboveapproximately 8 complete turns, the power also tends to increase anddecrease in a less proportional manner, especially as seen at 40 rpm.The turn range over which this proportional change occurs is typicallythe turn range within which a user would operate the exercise bike 100.

It may also be noted that there was a slight difference in measuredpower at a given adjustment member turn position and a given crank speedwhen increasing (i.e., power up) and decreasing (i.e., power down) theresistance. It is believed that these slight differences in measuredpower are a function of some relatively imprecise mechanical connectionsthat join the various braking and adjustment components together in thetest bike. Nonetheless, the proportional characteristics of power versusturns of the adjustment member 146 over a portion of the adjustmentrange were observed when both increasing and decreasing the resistanceat all crank speeds.

Returning to FIG. 13, the control knob 170 may be pressed down torelatively quickly slow down or stop the rotation of the flywheel 130.When the control knob 170 is pressed down, the adjustment member 146moves vertically downward. The vertical downward movement of theadjustment member 146 causes the link assembly 174 to move downward andthe right and left brackets 136, 138 to pivot towards the flywheel 130until the friction brake pad 196 engages a peripheral rim of theflywheel 130. Sufficient engagement of the brake pad 196 with theflywheel 130 causes a relatively rapid decrease in the rotation of theflywheel 130 that allows the user to relatively quickly slow down orstop the rotation of the flywheel 130. Upon release of the downwardforce, the bias member 148 returns the adjustment member 146 to itsoriginal position, thus disengaging the brake pad 196 from the flywheel130.

As shown in FIG. 13, as the friction brake pad 196 engages the flywheel130, the magnets 134 also overlap the flywheel 130. Thus, in addition tothe friction force applied to the flywheel 130 that resists rotation ofthe flywheel 130, the rotation of the flywheel 130 is also resisted bythe eddy current brake. Because of this additional eddy current brakingforce, the force that needs to be applied between the brake pads 196 andthe flywheel 130 for the friction brake to stop the flywheel 130 withina given time period for a given cadence may be less than the forcerequired for a comparable friction brake alone. In other words, it maytake less force input from the user to stop the flywheel 130 in a giventime period with the friction brake when combined with the eddy currentbrake than it does when the friction brake is not combined with an eddycurrent brake.

The exercise bike 100 may further include a monitoring system and aconsole 220. Turning to FIG. 17, the monitoring system may include aspeed sensor 222 for measuring the revolutions per unit time of theflywheel 130 and a power sensor 224 for estimating the power generatedby a user. The console 220 may be configured to show this and otherinformation to the user. The speed sensor 222, the power sensor 224, andthe console 220 may each be configured to transmit and receive signalsrepresenting information, such as speed or power, between thesecomponents via a wireless or wired connection.

The speed sensor 222 may be any suitable sensor that can measure therevolutions per unit of time (e.g., revolutions per minute) of arotating object, such as a flywheel. As an example, the speed sensor 222may be a magnetic speed sensor that includes a sensor and a sensormagnet. To protect the sensor, the sensor may be mounted in a sensorhousing, which may be mounted on the frame 106 of the exercise bike 100proximate the flywheel 130. The sensor magnet may be mounted on theflywheel 130 such that it periodically passes proximate the sensor asthe flywheel 130 rotates so that the sensor can determine how fast theflywheel 130 is rotating. The speed sensor 222 may send a signalindicative of the flywheel speed to the power sensor 224. The speedsensor 222 may also send a signal indicative of the flywheel speed tothe console 220. Although described in the example as a magnetic speedsensor, the speed sensor could be an optical speed sensor or any othertype of speed sensor.

With reference to FIG. 18, the power sensor 224 may include a powersource 226, an accelerometer 228, a microcontroller 230, a transceiver232 and an interface component 236. The transceiver 232, accelerometer228, microcontroller 230 and the interface component 236 may be mountedon a board. The board may be mounted on a power sensor housing forjoining the power sensor 224 to the brake assembly 132. Moreparticularly, the power sensor housing may be connected by mechanicalfasteners or other suitable connection methods to one of the brackets136, 138. Although FIG. 2 shows the power sensor 224 joined to the rightbracket 136, the power sensor could be joined to the left bracket 138.

The power source 226 provides power to the other components of the powersensor 224, including the accelerometer 228, the microcontroller 230,and the transceiver 232. The power source 224 may be one or morebatteries, such as double AA batteries, or any other suitable powersupply. The power source 224 may further include a power conditioner,such as TPS60310DGS single-cell to 3-V/3.3-V, 20-mA dual output,high-efficiency charge pump sold by Texas Instruments. The powerconditioner may be connected to the power source 226 to condition thevoltage provided from the power source 226 to a desired voltage. Theconditioned power may then be supplied to other components of the powersensor 224. The power source 226 may be mounted in the power sensorhousing and the power conditioner may be mounted on the board.

The accelerometer 228 facilities determining a tilt angle for thebrackets 136, 138 relative to a reference position. The tilt angle helpsdetermine power, which is described in more detail below. Forconvenience, the reference position may be calibrated in theaccelerometer using the upper stop position for the brackets 136, 138.However, other positions of the brackets 136, 138 relative to the framecould be used as the reference position. Once calibrated, theaccelerometer 228 may be used to measure changes in the position of thebrackets 136, 138 from the reference position as the brackets 136, 138are selectively moved relative to the flywheel 130 using the adjustmentmember 146 to increase or decease the resistance applied by the magneticfield to the flywheel 130. Using this measured position information, thetilt angle of the brackets 136, 138 relative to the reference positionmay be determined. For example, by knowing the changes in the x and ypositions of the accelerometer 228 from the reference position, an anglecan be calculated using geometrical equations, such as arc tan, thatrepresent the tilt angle of the brackets 136, 138. The accelerometer 228may be a MMA7260Q three-axis acceleration sensor sold by FreescaleSemiconductor or any other suitable acceleration sensor.

The microcontroller 230 may be an ATmega168PV-10AU microcontroller soldby Atmel Corporation or any other suitable microcontroller. Themicrocontroller 230 controls the other components of the power sensor224 and calculates information of interest, such as power or crankspeed. The microcontroller 230 may receive signals from the transceiver232 representing information of interest, such as the speed of theflywheel 130 (e.g., number of revolutions per minute), and providesignals to the transceiver 232 representing information of interest,such as the estimated power of the user. The microcontroller 230 mayalso receive information from the accelerometer 228, such as position ofthe bracket members 136, 138 relative to the reference point. Using thisinformation, the microcontroller 230 may determine the tilt angle of thebracket members 136, 138. The microcontroller 230 may also convert theflywheel speed to a crank speed. Yet further, using the determined tiltangle and either flywheel or crank speed, the microcontroller 230 may beused to estimate the user's power. This is described in more detailbelow.

To estimate a user's power, a power look-up table 234, such as the oneshown in FIG. 19, may be stored in the microcontroller 230. The powerlook-up table 234 may be based on the tilt angle from the referenceposition and the speed in revolutions per minute of the cranks. Usingthe tilt angle and the crank speed, the power corresponding to themeasured tilt angle and crank speed may be looked up in the table. Powervalues that correspond to specific tilt angles and crank speeds for usein the power look-up table may be determined by measuring and recordingthe power of one or more reference bikes at different tilt angles andcrank speeds using a dynamometer or other power measurement device. Whenmore than one exercise bike is used, the power values may represent anaverage of the power measured at respective tilt angles and crank speedsfor each bike. For speeds or tilt angles that fall between the valuesprovided in the power look-up table 234, the power may be determinedusing an interpolation method, such as bi-linear interpolation. Whilethe power look-up table 234 is shown as using crank speed to determinepower, in some embodiments the flywheel speed may be used in the powerlook-up table rather than the crank speed. Further, while the tiltangles and speeds are shown as ranging from 0 to 20 degrees for the tiltangle and 0-120 revolutions per minute for the speed, other ranges forthe tilt angles and speeds may be used in the power look-up table 234.

Because of manufacturing tolerances, differences in material propertiesof similar components, and so on, the powers measured for the referencebike and other exercise bikes at given tilt angles and crank speeds mayvary even though the bikes are constructed to be the same. To estimatethese differences, the power obtained from the power look-up table 234may be modified by one or more predetermined adjustment factors for eachexercise bike 100. For example, the power obtained from the powerlook-up table 234 may be adjusted by two adjustment factors. The firstadjustment factor may be used to account for differences between theexercise bike 100 and the reference bike in the mechanical drag of thedrive train system and the flywheel 130, and the second adjustmentfactor may be used to account for differences between the exercise bike100 and the reference bike in resistances provided to the flywheel 130by the magnetic field due to relative positioning of the magnets to eachother, different magnetic strengths of the magnets and so on. Forconvenience, the first adjustment factor may be referred to as themechanical drag adjustment factor, and the second factor may be referredto as the magnetic field adjustment factor.

The mechanical drag adjustment factor may be estimated using one or morebaseline spin-down tests or processes. More particularly, the right andleft brackets 136, 138 for the reference bike may be moved to the upperstop position. In the upper stop position, the flywheel 130 experienceslittle to no resistance from the magnetic field generated by the magnetsbecause the magnets do not overlap the flywheel 130. The flywheel 130for the reference bike may then spun up to a speed greater than apredetermined speed. After spinning up the flywheel 130, the flywheel130 is allowed to spin freely without further input, which results inthe speed of the flywheel 130 decreasing. Once the flywheel speedreaches the predetermined speed, the time it takes for the flywheel 130of the reference bike to slow down to a second predetermined speed ismeasured. A similar baseline spin-down is performed on the exercise bike100.

The time for the flywheel 130 of the exercise bike 100 to slow down fromthe first predetermined speed to the second predetermined speed iscompared to the time for the reference bike. If the time for theexercise bike 100 is less than the reference bike, the power from thelook-up table 234 is factored upward since the baseline spin downindicates that more power is required to reach similar flywheel speedsfor the exercise bike 100 than for the reference bike to overcomemechanical drag. If the time for the exercise bike 100 is greater thanthe reference bike, the power from the look-up table 234 is factoreddownward since the baseline spin-down indicates that less power isrequired to reach similar flywheel speeds for the exercise bike 100 thanfor the reference bike in order to overcome mechanical drag. Thecomparison for the baseline spin-down process may be performed using themicroprocessor 230. The mechanical drag adjustment factor may also bedetermined and stored using the microprocessor 230.

The magnetic field adjustment factor may be estimated using acalibration spin-down. The calibration spin-down is similar to thebaseline spin-down except the brackets 136, 138 for the reference bikeand the exercise bike 100 are positioned to a predetermined tilt anglesuch that the magnetic field generated by the magnets 134 resistsrotation of the flywheel 130. Like the baseline spin-down process, theflywheels 130 for both the reference bike and the exercise bike 100 arespun up above a predetermined speed and then allowed to slow down. Alsolike the baseline spin-down process, the time for the flywheels 130 ofthe reference bike and the exercise bike 100 to slow down from the firstpredetermined speed to a second predetermined speed are measured andcompared to establish the magnetic field adjustment factor for theexercise bike. Again, if it takes less time for the flywheel 130 of theexercise bike 100 to slow down than the flywheel for the reference bike,the power obtained from the look-up table 234 is adjusted upward by themagnetic field adjustment factor; if it takes more time, the powerobtained from the look-up table 234 is adjusted downward by the magneticfield adjustment factor.

In addition to differences in the mechanical drag and magnetic fieldsbetween exercise bikes 100, the power obtained from the look-up table234 may need to be altered by accelerations and decelerations of theflywheel 130. When the flywheel's speed is accelerated by a user from afirst speed to a second speed, the power required to reach the secondrotation speed is greater than the power required to maintain the secondrotation speed at a given resistance because of the inertia of theflywheel 130. Similarly, when the flywheel's speed is decelerated by theuser from a first speed to a second speed, the power required to reachthe second rotation speed is less than the power required to maintainthe second speed at a given resistance. To account for this poweradjustment for accelerations and decelerations of the flywheel 130, theaccelerations and decelerations of the flywheel 130 may be monitored bythe microcontroller 230 based on speed information received from thespeed sensor 224. When the microcontroller 230 determines the flywheel130 is being accelerated or decelerated, the power obtained from thelook-up table 234 may be adjusted by the following equation:

Power_((acceleration)) =I _(t)*α*ω

-   -   where,        -   I_(t) is the total drive train inertia;        -   α is the rotational acceleration at the cranks; and        -   ω is the rotation velocity at the cranks.            This acceleration power adjustment is positive for            accelerations and negative for decelerations. Further, when            the flywheel 130 rotates at a constant speed, this            adjustment factor is zero since the rotational acceleration            is zero.

In embodiments of the exercise bike 100 that include power adjustmentsfor mechanical drag, magnetic field and acceleration, the estimatedpower output by the user may be determined using the following equation:

Power_((user)) =P _((LUT))+(k ₁ +k ₂)*P _((LUT)) +P _((acceleration))

-   -   where,        -   Power_((user)) is the power output by the user;        -   P_((LUT)) is the power obtained from the lookup table based            on crank speed and tilt angle;        -   k₁ is an adjustment factor for mechanical drag;        -   k₂ is an adjustment factor for the magnetic field; and        -   P_((acceleration)) is the power of acceleration or            deceleration.            The foregoing equation is merely illustrative of one            potential equation for estimating the power of a specific            exercise bike. In other embodiments, the power may be            obtained from just the look-up power table 234 or may be            calculated using other approaches or methods to determine            the power.

For example, as another approach, power may be estimated using one ormore equations derived using power curves, such as the power curvesshown in FIGS. 16A-C, obtained from test data. The equations could thenbe used to estimate power as a function of one or more of turns of theknob 170 and crank or flywheel speed. Turns of the knob 170 could bedetermined by correlating turns of the knob 170 to the position measuredby the accelerometer 228 relative to a reference position. The one ormore equations could be complex polynomials that approximate relativelyaccurately the curves generated from the test data or could be lesscomplex polynomial or other equations that less accurately approximatethe curves. As an example of a less complex equation, three linearequations could be used to model the power curve at 40 rpms shown inFIG. 16A, with one linear equation modeling the curve up to about 4turns, the second linear equation modeling the curve from about 4 turnsto about 9 turns, and the third linear equation modeling the curve above9 about turns. Such an approach would tend to overestimate the power forless than 4 turns and underestimate the power for greater than 9 turns.Power between speeds for which there is not any test data to formequations could be estimated in the foregoing example by interpolatingbetween the results obtained using equations derived from speeds justbelow and above the desired speed. The foregoing example is merelyillustrative of one approach to using equations to estimate power for anexercise bike.

In sum, the power input by the user, which may also be referred to asthe user's power output, may be determined by the following steps. Withreference to FIG. 20, the tilt angle of the brackets and the crank speedof the exercise bike may be determined in step 250. In step 252, a poweris selected from the power look-up table 234 using the measured tiltangle and crank speed (or flywheel speed) or is determined using anequation. In optional step 254, the power obtained from the look-uptable 234 may then be adjusted by one or more adjustment factors toaccount for mechanical drag and differences in magnetic field strengthsbetween the exercise bike 100 and the reference bike and foraccelerations or decelerations of the flywheel 130. In step 256, thepower, either adjusted or unadjusted, may then be delivered to theconsole 220 via a signal for display on the console 220.

The transceiver 232 may transmit and receive signals from themicrocontroller 230, the speed sensor 222 and the console 220. Forexample, the transceiver 232 may receive a signal indicative of flywheelspeed from the speed sensor 222 and transmit this signal to themicrocontroller 230. As another example, the transceiver 232 may receivea signal indicative of power output by the user from the microcontroller230 and transmit this signal to the console 220. The foregoing examplesare merely illustrative and not intended to imply or require thetransceiver 232 to transmit or receive specific signals or to limit thetransceiver 232 to receiving and transmitting particular signals. Thetransceiver 232 may be a ANT11TS33M4IB transceiver sold by DynastreamInnovations Inc. or any other suitable transceiver.

The interface component 236 may be connected to the microcontroller 230.The interface component 236 allows the software for the microcontroller230 to be uploaded, debugged and updated. The interface component 236may be a six pin ISP/debugWire interface or any other suitableinterface.

The console 220 may include a display screen for displaying informationand a transceiver or the like for communicating with the power sensor224 and the speed sensor 222. The console 220 could receive data that isdisplayed without further processing, or could receive raw data thatwould be processed within the console 220 to convert the raw data intothe information that is displayed, such as power. The console 220 may bemounted on the handle bars 118 or on any other suitable location on theframe 106 where a user can access the console 220 while using theexercise bike 100. The console 220 may display information such power,cadence or speed, time, heart rate, distance, resistance level, and soon. The console 220 may also include a microcontroller or the like tocontrol other components of the console 220 or to perform calculations.

As described herein, an exercise bike may include a magnetic brakingsystem to resist rotation of a flywheel by a user. The magnetic brakingsystem may take the form of magnets mounted on brackets that may beselectively pivoted relative to the frame to increase or decrease theresistance opposing rotation of the flywheel. The brackets may bepivoted using an adjustment assembly joined to the brackets in such amanner that the magnetic forces resisting rotation of the flywheelincrease or decrease in a proportional manner over at least a portion ofthe adjustment range of the adjustment assembly.

The exercise bike may further include a console that displaysinformation, such as power. The power may be estimated from a look-uptable using the crank or flywheel speed of the exercise bike and thetilt angle of the brackets relative to a reference point. The look-uptable may be created by measuring the power of a reference bike forvarious crank or flywheel speeds and tilt angles. The flywheel speed maybe measured using a speed sensor joined to the exercise bike, and thetilt angle may be using measured using a power sensor that includes anaccelerometer. The power obtained from the look-up table may be adjustedby adjustment factors to account for differences, such as mechanicaldrag and magnetic field variations, between the exercise bike and thereference bike. The adjustment factors may be determined using one ormore spin-down tests or processes. The power may be further adjusted bytaking into account the power associated with accelerations anddecelerations of the flywheel by the user.

All directional references (e.g., upper, lower, upward, downward, left,right, leftward, rightward, top, bottom, above, below, vertical,horizontal, clockwise, and counterclockwise) are only used foridentification purposes to aid the reader's understanding of theembodiments of the present invention, and do not create limitations,particularly as to the position, orientation, or use of the inventionunless specifically set forth in the claims. Connection references(e.g., attached, coupled, connected, joined, and the like) are to beconstrued broadly and may include intermediate members between aconnection of elements and relative movement between elements. As such,connection references do not necessarily infer that two elements aredirectly connected and in fixed relation to each other.

In some instances, components are described with reference to “ends”having a particular characteristic and/or being connected with anotherpart. However, those skilled in the art will recognize that the presentinvention is not limited to components which terminate immediatelybeyond their points of connection with other parts. Thus, the term “end”should be interpreted broadly, in a manner that includes areas adjacent,rearward, forward of, or otherwise near the terminus of a particularelement, link, component, part, member or the like. In methodologiesdirectly or indirectly set forth herein, various steps and operationsare described in one possible order of operation, but those skilled inthe art will recognize that steps and operations may be rearranged,replaced, or eliminated without necessarily departing from the spiritand scope of the present invention. It is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative only and not limiting. Changes indetail or structure may be made without departing from the spirit of theinvention as defined in the appended claims.

1. An exercise bike, comprising: a frame; a drive train operativelyassociated with the frame; a flywheel operatively associated with thedrive train; and a braking assembly comprising: an adjustment memberdefining a longitudinal axis; a magnetic brake comprising: a firstbracket joined to at least one first magnet, operatively associated withthe frame, and positioned proximate the flywheel; and a second bracketjoined to at least one second magnet, operatively associated with theframe, and positioned proximate the flywheel; and a link assemblyincluding at least one link operatively associated with the adjustmentmember, the first bracket, and the second bracket; and the adjustmentmember, the magnetic brake and the link assembly are configured suchthat rotation of the adjustment member around the longitudinal axis ofthe adjustment member moves the first bracket and second bracket via theat least one link between at least first and second positions where atthe first position the at least one first magnet and the at least onesecond magnet at least partially overlap the flywheel to operativelyassociate the magnetic brake with the flywheel and at the secondposition the at least one first magnet and the at least one secondmagnet do not overlap the flywheel to operatively disassociate themagnetic brake with the flywheel.
 2. The exercise bike of claim 1,wherein the adjustment member, the magnetic brake, and the link assemblyare further configured such that for at least a portion of an adjustmentrange, an incremental rotation of the adjustment member causes asubstantially proportional change in a resistance exerted by themagnetic brake on the flywheel.
 3. The exercise bike of claim 1, whereinthe link assembly further includes a link plate movably joined to theadjustment member, the at least one link is operatively associated withthe adjustment member by pivotally joining the at least one link to thelink plate, and the at least one link is operatively associated with thefirst bracket by pivotally joining the at least one link to the firstbracket.
 4. The exercise bike of claim 3, wherein: the at least one linkdefines a link longitudinal axis; in the second position, the linklongitudinal axis extends at an angle from the longitudinal axis of theadjustment member; and as the first and second brackets move from thesecond position to the first position, the at least one link pivotsrelative to the link plate and the first bracket in such a manner thatthe link longitudinal axis more closely aligns with the longitudinalaxis of the adjustment member at the first position than at the secondposition.
 5. The exercise bike of claim 1, further comprising a frictionbrake operatively associated with the adjustment mechanism for selectiveengagement with the flywheel.
 6. The exercise bike of claim 1, whereinthe flywheel includes an inner radial portion formed of a first type ofmaterial and an outer radial portion formed of a second type of materialdifferent than the first type of material.
 7. The exercise bike of claim6, wherein the second type of material comprises a non-ferrous,conductive material.
 8. The exercise bike of claim 7, wherein the firsttype of material comprises steel and the second type of materialcomprises aluminum.
 9. An exercise bike, comprising: a frame; a drivetrain operatively associated with the frame; a flywheel operativelyassociated with the drive train; a braking system operatively associatedwith flywheel; and a power sensor operatively associated the brakingsystem, the power sensor including an accelerometer that measures aposition of the braking system relative to a predetermined referencepoint.
 10. The exercise bike of claim 9, further comprising a speedsensor operatively associated with the flywheel to measure a speed ofthe flywheel.
 11. The exercise bike of claim 10, the power sensorfurther comprising a transceiver configured to receive a signalindicating the speed of the flywheel.
 12. The exercise bike of claim 11,the power sensor further comprising a microcontroller configured toreceive the signal indicating the speed of the flywheel and a signalindicating the position of the braking system and to estimate a powerbased on the received signals.
 13. The exercise bike of claim 12,further comprising a console configured to receive a signal indicatingthe estimated power and to display the estimated power.
 14. A method forestimating a power of an exercise bike, comprising: measuring arotational speed of a flywheel of the exercise bike; measuring a tiltangle of a magnetic brake operatively associated with the flywheel; andestimating power using the measured rotational speed and the measuredtilt angle.
 15. The method of claim 14, further comprising measuring thetilt angle with an accelerometer.
 16. The method of claim 14, whereinestimating the power further comprises utilizing a look-up tablecontaining power values.
 17. The method of claim 16, wherein estimatingthe power further comprises adjusting the power value obtained from thelook-up table by at least one adjustment factor.
 18. The method of claim17, wherein the at least one adjustment factor is selected from a groupconsisting of a mechanical drag adjustment factor or a magnetic fieldadjustment factor.
 19. The method of claim 18, wherein at least of onethe mechanical drag adjustment factor or the magnetic field adjustmentfactor is based on a spin down process.
 20. The method of claim 16,wherein estimating the power further comprises measuring a change in therotational speed of the flywheel and adjusting the power value obtainedfrom the look-up table by an acceleration power associated with thechange in the rotational speed of the flywheel.